These correlated with the number of years tuners had been doing this job.

The Wellcome Trust researchers used magnetic resonance imaging to compare the brains of 19 professional piano tuners - who play two notes simultaneously to make them pitch-perfect - and 19 other people.

What they saw was highly specific changes in both the grey matter - the nerve cells where information processing takes place - and the white matter - the nerve connections - within the brains of the piano tuners.

Investigator Sundeep Teki said: "We already know that musical training can correlate with structural changes, but our group of professionals offered a rare opportunity to examine the ability of the brain to adapt over time to a very specialised form of listening."

Other researchers have noted similar hippocampal changes in taxi drivers as they build up detailed information needed to find their way around London's labyrinth of streets.

Prof Tim Griffiths, who led the latest study, published in Neuroscience, said: "There has been little work on the role of the hippocampus in auditory analysis.

"Our study is consistent with a form of navigation in pitch space as opposed to the more accepted role in spatial navigation."